The FAA has issued a notice of a proposed Airworthiness Directive (AD) that is applicable to all IO-360 and O-360 series of engines manufactured by Superior Air Parts (SAP) and some Lycoming AEIO-, IO- and O-360 engines that incorporate certain crankshaft assemblies supplied by SAP under PMA (Parts Manufacturer Approval) rules.

Crankshaft assembly failures in three separate incidents that led to emergency landings is what prompted the FAA to step in.

“Unfortunately, we were only informed of the proposed rule two weeks ago. Since then, we have been in contact with the FAA regarding their findings to fully understand the issue and identify the most likely cause of the failures,” SAP V-P of marketing Scott Hayes said. “Our engineering team is currently reviewing all of the available information, and once we have determined the actual cause, we can work with the FAA to determine the most logical course of action.”

According to SAP, the affected crankshafts carry part numbers SL36500-A20 or SL36500-A31, with serial numbers 82976-01, 82976-02, SP12-0003 through AP12-0089 inclusive; SP13-0034 through SP13-0150 inclusive; or SP14-0151 through SP14-0202 inclusive.

“All I can say for certain is that it is still just too early to form any type of conclusion about what caused these three crankshafts to fail the way they did,” added Bill Ross, SAP’s VP of product support.

View the proposed AD here.

Photo credit: SAP